JOHANNESBURG - Free State police have confirmed the bus crash that killed at least 10 African National Congress (ANC) volunteers near Winburg in the Free State was caused by the two drivers swapping seats while the vehicle was in motion.

Yesterday, the bus transporting volunteers from Katlehong in Ekurhuleni veered off the road after the driver lost control of the vehicle leaving more than 50 people injured.

While it was initially believed driver fatigue was involved, it appears negligence may have played a role.

Free State police say a 31-year-old bus driver has been taken in for questioning regarding his apparent role.

A second driver is still in a being treated for injuries.

The police's Malebo Khosana says both drivers will be charged with culpable homicide.

STRONG ACTION PROMISED IN THE WAKE OF THE FATAL CRASH

Meanwhile, Kabati Transport has assured the families of the victims that a full investigation will be carried out and there'll be no leniency for anyone found guilty of negligence.